fix(bottom-sheet): focus trap not being attached when autoFocus is disabled (#15125)

Fixes the bottom sheet container not creating a focus trap, if `autoFocus` is set to `false`.

Fixes #15119.

src/lib/bottom-sheet/bottom-sheet-container.ts

@@ -146,7 +146,7 @@ export class MatBottomSheetContainer extends BasePortalOutlet implements OnDestr
   _onAnimationDone(event: AnimationEvent) {
     if (event.toState === 'hidden') {
       this._restoreFocus();
-    } else if (event.toState === 'visible' && this.bottomSheetConfig.autoFocus) {
+    } else if (event.toState === 'visible') {
       this._trapFocus();
     }
 
@@ -187,7 +187,9 @@ export class MatBottomSheetContainer extends BasePortalOutlet implements OnDestr
       this._focusTrap = this._focusTrapFactory.create(this._elementRef.nativeElement);
     }
 
-    this._focusTrap.focusInitialElementWhenReady();
+    if (this.bottomSheetConfig.autoFocus) {
+      this._focusTrap.focusInitialElementWhenReady();
+    }
   }
 
   /** Restores focus to the element that was focused before the bottom sheet was opened. */

src/lib/bottom-sheet/bottom-sheet.spec.ts

@@ -547,6 +547,20 @@ describe('MatBottomSheet', () => {
           'Expected bottom sheet container to be focused.');
     }));
 
+    it('should create a focus trap if autoFocus is disabled', fakeAsync(() => {
+      bottomSheet.open(PizzaMsg, {
+        viewContainerRef: testViewContainerRef,
+        autoFocus: false
+      });
+
+      viewContainerFixture.detectChanges();
+      flushMicrotasks();
+
+      const focusTrapAnchors = overlayContainerElement.querySelectorAll('.cdk-focus-trap-anchor');
+
+      expect(focusTrapAnchors.length).toBeGreaterThan(0);
+    }));
+
     it('should focus the first tabbable element of the bottom sheet on open when' +
       'autoFocus is enabled', fakeAsync(() => {
         bottomSheet.open(PizzaMsg, {